<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title></title>
</head>
<body>
	<ul>
		<li class="item">1</li>
		<li class="item">2</li>
		<li>3</li>
		<li id="li">4</li>
		<li>5</li>
	</ul>
	<script type="text/javascript">
		// querySelector("css选择器") 默认获取第一个元素
		let item = document.querySelector("ul .item")
		console.log(item)

		// querySelectorAll("css选择器") 获取满足所有条件的元素 返回伪数组
		let items = document.querySelectorAll("ul .item")
		console.log(items)

		//id
		let li = document.querySelector("#li")
		console.log(li)
	</script>
</body>
</html>